Heard A Volcano Is About To Erupt? You Should Read This First

Mt Agung going through an effusive type eruption on full moon night, here backlit by the setting moon and front lit by the first rays of the sunrise. (Rio Helmi/LightRocket via Getty Images)

I’m going to make you a bet. I reckon within the next week, a story about a volcano somewhere in the world will make headlines that, at the very least, imply an eruption is around the corner.

There are, as it happens, several dozen volcanoes erupting at any one time on this silly, wonderful planet of ours. These nail-biting stories, however, focus on those that have been quiet recently and, the whispers say, are gearing up for something big. These tales are a dime a dozen, and if you’ve been paying careful attention to the news, you’ll also notice that they’re complete garbage. If much of the media had its way, you’d be seeing volcanoes erupting left, right and center all over the shop, and the planet would be smothered in ash and lava and death – and yet, here we are, alive and stupefied.

It’s completely fair to say that it’s not easy to tell truth from fiction on some occasions. If you glanced at the headlines earlier this week, and plenty of the stories that accompanied those headlines, you’d have thought that Iceland’s Katla, a genuinely hazardous volcano, was about to erupt. Even outlets normally known for being a little more sensible on the science side of things were heralding an event that would make the 2010 Eyjafjallajökull event look a little pathetic.

This obviously never came to pass, and the study that these bonkers, frightening claims were based on had nothing at all to do with predicting when the next Katla eruption would occur, nor what style of eruption it would be, how powerful it would be, or how damaging it would be to anyone in any form. As I explained here in my short debunker, the paper was in fact a great insight into Katla’s funny tummy, but not a looking glass into when it might next savage the landscape or the air above it.

So – without further ado – here’s a fool-proof guide to knowing if that volcano everyone’s seeming to panic about is going to erupt or not.

They key thing to remember is that predicting when volcanoes will erupt at present isn’t possible to any degree of precision. That’s why, if you see headlines that use phrases like “imminent”, “catastrophic”, “deadly” or “about to blow”, you shouldn’t trust them, because scientists wouldn’t ever make such clear, bold, definitive claims like this.

Some forecasting is, however, possible. Unlike earthquakes, which don’t seem to give off any warning signs indicating when they are about to take place, volcanoes sometimes do. These warning signs may take several forms: increased thermal output, ground deformation, increased emission of certain volcanic gases, specific types of seismic signals, and so on. These could be signs that magma is moving up through the crust and near to the surface. Based on what scientists know about this volcano’s history, and others like it, they weigh up how likely a volcano is going to erupt in some way or another and make conservative guesses as to when.

The massive, neon-coated caveat here is that these signs might mean something else entirely. The ground around Yellowstone deforms often, and there are plenty of earthquakes, but these are clearly related to the movement of hydrothermal fluids underground, and the local extension of the crust by large-scale tectonic processes.

View of the 'Old Faithful' geyser which erupts on average every 90 minutes in the Yellowstone National Park, Wyoming on June 1, 2011. (MARK RALSTON/AFP/Getty Images)

The ground also deforms, on occasion, quite dramatically around Italy’s Campi Flegrei, a not-quite-supervolcano whose violent past is cause for some concern in the present. Here, however, what’s driving the movement is a littleunclear, and a sudden, rapid inflation in the 1980s – followed by a subsequent deflation – makes it clear that this alone is no precursor to an eruption.

It cannot be stressed enough that each volcano is different. The warning signs may be broadly similar for all volcano types, but some are far more unpredictable than others. Those that haven’t erupted in eons are harder to forecast for, because there’s not enough history to go on.

Katla, for example, has a somewhat decent eruption history as recorded by humans, but even with 20 major events in the last 1,100 years, forecasting is tricky – there’s just no clear pattern to its eruptive activity. Sicily’s Stromboli, on the other hand, erupts roughly once every 30 minutes in spectacular displays of lava fountaining, just as it’s done so for several millennia. This predictability is partly why it’s the target of so much cutting-edge volcanic research: matching up eruptions to warning signs is far easier, and – as a general rule of thumb – the more often a volcano erupts, the less hazardous it is to humans.

Whether we have a decent eruption history or not is irrelevant for many volcanoes. Unlike, say, America’s Mount Rainier, many volcanoes elsewhere in the country – and around the world – are poorly monitored. They either have out of date equipment, or they don’t have any. Even with a decent eruption history on record, then, an eruption here can take people by surprise and sometimes prove to be fatal.

There’s a lot more to it than that, but hopefully by this point it’s very clear that predicting when a volcano will erupt, and how it will erupt, isn’t something any scientist can say with any precision. Best guesses may be given, but if you look at how volcanologists speak about hazardous volcanoes, they almost always stress that they can’t say when it will erupt next. They can talk about the various hazards a volcano presents, and how it’s erupted in the past, but the future is full of caution.

A sudden volcanic eruption can be deadly, sure. Headlines about imminent eruptions that will be utterly catastrophic, however, are damaging too: they knock confidence in science, science journalism, and – often – the local economies of these locations that often heavily rely on tourism.

Sadly, false prophecies of paroxysmal eruptions happen all the time, and it’s easy to see why: they drive clicks and views. Even if the story remains rational, the headline can be used to draw in those fearful of the next micro-apocalypse. If you go to Google News and search for volcanic eruption, rather regrettably, you tend to get links to sites that really skimp on the facts and go straight for the sensationalism.

Any whiff of any new volcano news sets off unnecessary alarm bells. Papers that are often about the underlying magmatism of volcanoes tend to get taken way out of proportion, particularly if they’re that hugely misleading type of volcano, the “supervolcano.” Yes, supervolcanoes are fascinating, but as I’ve explained here, they aren’t what you think they are. Their colossal blasts from the past are no guarantee that they’ll perform similar feats ever again.

Not too long ago, reports were going around that a supervolcano was forming in New England. In this case, there wasn’t even a volcano, just a thermal anomaly that, perhaps in 50 million years or so, lead to a volcanic system. Maybe. And yet, headlines screamed and misinformation abounded.

Lava erupts from the Rivals crater flowing down the south face of the Piton de la Fournaise. (RICHARD BOUHET/AFP/Getty Images)

With some obviousexceptions, you can’t be sure whether a news outlet is intentionally misleading people when it comes to volcanic eruptions, or whether they have just got the wrong end of the stick and didn’t dig down into the facts as they should have. Either way, the same mantra applies: don’t buy scary headlines or stories without checking your sources.

Unless authorities like the USGS, or the equivalent in other parts of the world, are saying a volcano is showing dangerous signs of an eruption, then you can probably bet that that volcano in question isn’t about to erupt. Just remember: how many times has Yellowstone shown “signs” of an eruption this year alone? Even the hyper-active nature of some of its hot springs and geysers as of late has been a cause for worry, but again, the USGS et al. has not said anything about an eruption – apart from the absence of one in the near-future, that is.

Janine Krippner, a volcanologist at Concord University and smiter of ludicrous volcanological rumours, explains that it helps to know where to go for hard facts. There’s a great list of resources here, but at the very least, you should look to the volcanologists themselves, who are often very active on social media, particularly Twitter, these days. They’re the ones that spend their lives researching these volcanoes, so they would know what the situation on the ground is like.

“We will continue to shoot down bad information and direct you to sources you can trust,” she says. “We are here to help, we deeply care about those affected by volcanoes, and we will not stop working towards improving how we communicate so that you have access to the right information.”

Robin George Andrews is a doctor of experimental volcanology-turned-science journalist. He tends to write about the most extravagant of scientific tales, from eruptions and hurricanes to climate change and diamond-rich meteorites from destroyed alien worlds - but he's always...